I really am not sure how easy it is to put a body lift on a sidekick with an auto tranny. I know that with a manual it's a little easier because you don't have the auto console there, and you can just bend or extend the stick and it works fine. You might be taking the auto console out to make shifting room once you have a body lift?
That's really my only concern. Other than that, a body lift on a 4 door is pretty easy. (I did it myself, my husband came home and tightened the bolts). After having done a custom body lift though, I would highly recommend you purchase an actual manufacturers body lift, as I think I ran into more trouble than I would have if I had done it that way.
If it were a perfect world, I would recommend getting a Calmini 2 inch suspension front with a 3 inch rear. Mainly because of the extended heim joint and control arms for the rear. I REALLY liked the ride of the 2 inch up front, and I DON'T have a camber issue and I DON'T have CV joint problems and I DON'T have problems popping bolts or ripping aluminum out of my diff mounts.
Well. The only Calmini 2 inch items still residing on my truck at this point are the a-arms, the drop brackets, and the front struts. I changed over the springs in the back to stock TJ's, and the shocks in the back to Rancho RS 5115's (more droop). I changed the springs in the front to some no name out of the used bin at a local spring shop 2 inch longer, thicker and tighter wound ones.
The hardest part about a 4 door is the heavy butt. Gotta make something up to keep it from sagging and rubbing on the tires.
I would recommend the 3 inch lift (watch those CV joints and camber issues) because you get the extended rear heim joint and control arms, which make 31's easier to fit, and then get some spring spacers for the rear to help keep it up. You can use Jeep TJ spacers from Daystar (most 4x4 shops in town should be able to get them) and bore the centers out about 1/4 inch, or go with the ones Rocky Road has.
If you are buying a Sport Sidekick, you might need to do some modifications to the Calmini suspension lift to get it to fit right, because the frame is wider on the Sport. See this site:
I understand that us americans don't get the V-6, but the frame is the same. We have a friend who lives in the next town over who has a lifted Sport, and he also had to modify the suspension lift.
Sorry for the long post. I REALLY like lifted 4 doors, and wish I could see more of them. They handle really well because of the long wheelbase, their only shortcoming being the breakover angle.